No abstract

Usually model parameters from uniaxial experiments are not suitable for dielectric elastomer under biaxial loading condition. To characterize the mechanical behavior of dielectric elastomer, a biaxial tensile bench is established, on which uniaxial tests can be performed too. On the basis of the analysis of viscous effect of elastomer, experimental condition for data acquirement is determined. Then equi-biaxial and uniaxial experimental data are obtained to fit three constitutive models, i.e. Mooney-Rivlin, Yeoh and Ogden model. Also, least square minimization method is used to obtained model parameters, which are applicable to both uniaxial and equi-biaxial experimental data.

To enhance the velocity profile’s smoothness and machining efficiency of continuous short line segments, a velocity smooth control algorithm was presented based on the transition of cubic parametric spline curves. The transitional mathematical model was constructed, and an improved S-shaped jerk-limited acceleration/deceleration algorithm with look-ahead was adopted for smoother velocity profiles. The simulation and experiment results showed that machining efficiency was greatly improved, and smoother velocity profile was achieved, which approved the feasibility and validity of the proposed method.

In motion control systems driven by stepping motors, reference word interpolation is usually used with a constant period, which inevitably results in vibration caused by quantization errors and interpolation spare. An interpolator with adaptive random-period is proposed: with the adaptive random-period interpolator, the high-frequency energy excitation from stepping motor driving signals can be greatly dispersed and the desired trajectory and feed profile can be realized through the mutual restriction between the velocity and the displacement. Simulation results show that the adaptive random-period interpolator can effectively improve the velocity excitation, resonant excitation and motion accuracy.

In motion systems driven by stepping motors, reference word interpolation is usually used with a constant period T, in which the existing position quantization errors will inevitably result in the trouble of velocity quantization errors. A separated-axis interpolator with variable period is proposed to deal with these troubles. The reassignment module of displacement and time is the key of the interpolator. In the module, the interpolation period of each axis can be separately adjusted upon its quantized displacement, thus resulting in almost ideal velocity profile and moving smoothness. Simulation and machining results are given and show that the proposed interpolator is effective in the improvement of motion stability and interpolation accuracy.